Do trees flower longer in the city? A comparison of flowering eucalyptus trees in streets, remnants and continuous forest and their association with nectarivorous birds

Abstract

Human-dominated environments are often subjected to increased nutrient and moisture regimes which have the potential to influence the flowering phenology of plants. Protracted flowering periods within urban landscapes may result in increased food resources, in the form of nectar, and this high resource availability may support a high density of nectarivorous birds within cities. In order to determine whether there was a difference in the productivity and flowering period associated with urbanisation, we compared the number of flowers produced and duration of flowering period for three species of native tree that were present in streetscapes, remnant vegetation and continuous forest. We also recorded the presence of nectarivorous parrots at flowering trees to determine if the presence of nectarivores was associated with flower productivity. All three species in streetscapes produced more flowers and flowered for longer than in remnants and continuous forest. The number of flowers per tree significantly predicted the presence of nectarivorous parrots in streetscapes. This study demonstrates that the flowering phenology of plants within streetscapes can differ from continuous forest, with remnants appearing to be intermediate. This increased flower productivity within urban landscapes may be partially responsible for the high abundance of nectarivorous parrots within some cities.